Bluetooth keyboard as a foot controller

Hi, I need really simple foot controller for Loopy on iPhone. Something like iRig BlueBoard. I read a couple of threads here, but didn't find any satisfying ideas. If I buy a bluetooth keyboard, remove unwanted keys, connect Loopy and keyboard via Bluetooth and then try to bind keys with specific actions, it will work? Or maybe you can give me some advice on how to do it. Thank you in advance and also sorry for my English, but it isn't my native language

I did this for awhile and it works great, but (at least when I tried it) the keyboard doesn't continue to work if you switch focus to a different app. It's a great way to cheaply figure out how many buttons you need and what you want them all to do.